Cadmium from environmental sources may non-lethally affect many different physiological functions (including adrenocortical function), particularly because clearance half-time exceeds 12 years. Cd++ non- lethally reduces basal and ACTH stimulated adrenocortical steroidogenesis in vitro and in vivo, interfering with steroid modulation of the bodies' over-response to stress. Affects of non- lethal Cd++ levels on the cultured Y-l mouse adrenal-cell model will be studied. Specific study aims include characterizing the: l. competition between Cd++ and Ca++ ions for plasma membrane adenyl cyclase sites; 2. CdCl-2 inhibition of mitochondrial cholesterol and 25-hydroxy-cholesterol utilization; 3. Cd++ effects on Y-l cell hyperplasia. Preliminary data suggesting that CdCl-2 inhibited plasma membrane adenyl cyclase activity through a Cd++ -Ca++ competition will be confirmed using lesser Cd++ and Ca++ concentrations. Secondly, a collaboration will be established to use patch-clamping for studying Cd++-Ca++ plasma membrane transport phenomena in adrenal cells. To investigate mitochondrial 25-hydroxy and endogenous cholesterol metabolism, adrenal cells will be "loaded" with tritium labeled compounds, incubated with or without ACTH in the presence or absence of Cd++, mitochondria will be isolated, inner and outer membranes will be obtained, and label will be quantitated. To determine whether Cd++ affects mitotic/hyperplastic activity of unstimulated and stimulated Y-l cells, cell numbers, cell viability, DNA content, and cell cycle duration will be measured: a) after each of four daily cell harvest of populations initially exposed to low, medium, or high CdCl-2 concentrations for 0.5, 2, or 4 hours then incubating without Cd++, or b) daily harvest during chronic exposure of populations to low, medium, or high concentrations presented over the entire 4 day growth period.